An effort to prepare synthetic maytansine is underway. This potent anti-tumor macrolide, currently in clinical trials, possesses many unique structural features and its total synthesis is therefore a formidable task. A number of analogs are being prepared in an attempt to assess which, if any, portion of the molecule possesses significant anti-tumor activity. BIBLIOGRAPHIC REFERENCES: D.M. Stout, T. Takaya and A.I. Meyers, "An Unequivocal Synthesis of N-Substituted 1,4-Dihydropyridines", J. Org. Chem., 40, 563 (1975). A.I. Meyers, C.C. Shaw, and Deane Horne; and L.M. Trefonas and R.J. Majeste, "Progress Toward the Total Synthesis of Maytansine. A Stereoselective Synthesis of the C-1 to C-7 Moiety (Northern Zone), Tetrahedron Letters, 1745 (1975).